This is a 371 of International Application No. PCT/EP98/07413 filed Nov. 19, 1998.
The present invention refers to a device allowing to store a plurality of liquid or semi-liquid (flowable) reagents, required for a given chemical or biochemical synthetic or test reaction, in integrated form, i.e. in a single container that is easy to produce and to handle, and, in use, the device further allowing for an exact dosing of such reagents in a reaction chamber without any prior mixing of the reagents by a simple linear movement of a plunger.
Integrated storage and defined dosing of a plurality of liquid or semi-liquid reagents is of great importance for the production of ready-to-use chemical and pharmaceutical products which are chemically complex, i.e. wherein various, sometimes very different reagents that react with each other have to be supplied in doses into a reaction chamber in a chronologically defined sequence, and which also must be easy to produce and to handle by the user. A sufficiently simple handling is realized in particular when the user can trigger the dosing by only a few unmistakable manipulations.
Important fields of application are the chemical and biochemical fast analytics and in active substance formulating for pharmaceutical purposes. Clinical fast analytics is of particular commercial importance. Here, simple integrated systems are needed that operate reproducibly and, possibly, quantitatively, which can be used in decentral applications (doctor""s offices, pharmacies, households) even by non-skilled users. A typical list of requirements concerning the handling and reliability has been established In the US in the guidelines to the CLIA (clinical laboratory improvement act).
A device presently used in fast analytic for storing and dosing of a maximum of three different reagents is described In U.S. Pat. No. 4,943,522. Here, a biochemically active component is applied to a strip-shaped glass tissue and dried thereon. Dried, it can be stored over a longer period. The glass tissue is placed over a strip of cellulose nitrate. In use, a liquid sample is applied that penetrates the glass tissue due to capillary forces acting and dissolves the reagents stored there, thus initiating a partial reaction. The reaction mixture will then penetrate further Into the cellulose nitrate membrane, where a second and, possibly, a third reactive component is present reacting further with the sample. This method is not practical for reactions requiring more than three reagents, since, in general, mixing an/or netting reactions between the components occur that are difficult to control. Intermediate washing steps to avoid these effects are not possible. Specifically, the device does not provide a very good quantitative evaluation since the basic phyisco-chemical steps such as drying, reconstitution and lateral diffusion are very sensitive to interferences and cannot well be reproduced without great technical effort. Therefore, preference is given to liquid reagents. A corresponding device for storing and dosing is described in WO/A/9718895. It Is based on the use of at least two rigid storage receptacles/containers holding the reagents. The containers are disposed one behind the other and are each closed at the bottom by means of a closing means that can be opened through a trigger means. In use, the reagents flow through the open bottoms due to gravity and into the underlying container and from the last container out from the device and into the reaction chamber. On principle, the dosing may be performed in two ways. Either, the closing means of the individual containers are opened sequentially, starting with the container nearest the outlet opening to the reaction chamber, the higher container being opened only when the lower container is empty, or all containers are opened simultaneously with liquids from higher containers flowing into a lower container not yet empty. In the first case, a multiple triggering of the dosing is necessary. This is tedious to the user and not acceptable for many applications. In the second case, partial mixing cannot be excluded. Generally, this leads to uncontrollable pre-reactions or dilution. The above application suggests to minimize these effects by neutral additives that change the density and the viscosity of the liquids. However, this does not exclude reactions at phase interfaces and mixing caused by microturbulences.
Another disadvantage of the above device is the control of the dosing by gravity in combination with the flow resistance of the application device and, possibly, the connected reaction chamber. Since the flow resistance within the containers depends very strongly on the interfacial tensions of the liquids, small added amounts of surface active substances, e.g., can have strong effects on the flow characteristics. In applications where, for reaction-kinetic reasons, a reproducible outflow behavior of the reagents is required, this causes very large variations in the course of the reaction.
It is an object of the present invention to provide a device which enables, in a simple manner, a precise, chronologically defined and sequential discharge of at least two liquid or semi-liquid reagents into a reaction chamber by a single mechanical linear movement, without prior mixing of the reagents,
According to the present invention, a device is employed wherein the individual reagents are disposed one behind the other in the form of a reagent column, the individual reagents segregated by movable partitions that are slidably supported in a sealing manner at the inner surface of a cylindrical container holding the reagent column.
For dosing, the segregated reagent column is advanced towards and through an outlet opening, the reagents leaving the container accordingly and the partitions being advanced into a portion of the container that is below the inlet opening of the outlet channel. Here, the media contained in this portion of the container is pushed either into the environment or into the reaction chamber via a pressure compensation channel. In the first instance, the pressure compensation channel is open to the environment and the media is air. In the second instance, the pressure compensation channel is open to the reaction chamber and the media is a liquid to be dosed, e.g. a washing solution.
Further, a holding force generating unit is integrated in the device, which, together with the first lower partition, seen in the discharge direction, generates a pressure counteracting the linear movement and higher than the pressure generated by the pressure generating unit. Here, it is possible, for example, to provide a spring between the bottom of the receiving container and the first partition. A particularly simple solution is to use a first partition having a slightly higher friction that the subsequent partitions, due to a larger outer diameter. An analogous effect may be obtained if the receiving portion below the inlet opening of the outlet channels has a slightly smaller inner diameter, e.g., by 1-10%, than the superjacent portion of the receiving chamber, or if it has a higher friction due to special surface treatment.
In an advantageous development of the invention, it is provided that the pressure generating unit is a plunger or rod abutting the inner surface of the receptacle in a sealing manner and being slidable towards the first end of the receiving chamber. Since the topmost reagent volume in the reagent column is usually sealed off by a partition element, this partition element acts as a plunger onto which the rod of a pressure generating device acts. The pressure generating device may also be designed as a pneumatic pressure generating unit acting pneumatically on the topmost partition element. Hydraulic systems are also conceivable as the pressure generating unit.
Suitably, the outlet opening is joined by an outlet channel which extends beyond the first end of the receptacle. This outlet channel is disposed either outside or within the receiving chamber. When disposed within, it is designed as an outlet tubule whose end arranged in the receiving chamber can pierce the partition elements when these move towards the first end of the receptacle due to the pressure exerted by the pressure generating unit. Here, the outlet tubule directed opposite to this direction of movement.
Should the portion of the receiving chamber between the outlet opening and the relief opening merely hold air or a gas, it is suitable to direct the relief opening into the environment around the receptacle. It is also possible that a reagent is present in this portion of the receiving space. It is then suitable to have the relief opening in fluid communication with the outlet opening, for example, by making the relief opening terminate in the outlet channel.
Specifically, the holding force generating device is a unit increasing the friction between the lowermost partition element in an area between the outlet opening. The increased static friction thus obtained guarantees that at least the lowermost partition element is not moved any further when reaching the portion of the receiving chamber below the outlet opening, so that the pressure accumulated by the pressure generating unit is used to discharge the reagent above the lowermost partition element through the outlet opening. When the next partition element comes into the vicinity of the outlet opening and closes the same, the pressure from the pressure generating device will move the two overlying partition elements towards the first end of the receiving chamber until the upper one of these two partition elements is situated below the outlet opening. Now, the reagent of the volume above this partition element may flow off through the outlet opening. This process is repeated corresponding to the number of partition elements and reagent volumes.
Increased friction in the portion below the outlet opening of the receiving chamber may, for example, be effected by a corresponding treatment of the contacting surfaces of the lowermost partition element and the inner surface of the receiving chamber. It is also conceivable to provide a constriction in a portion of the receiving chamber below the outlet opening or to configure the lowermost partition element oversized with respect to the other partition elements, i.e. wider than the other partition elements. Finally, it is also conceivable to use a spring as the holding force generating unit whose resilience acts opposite to the direction of the partition elements along which these move under the action of the pressure from the pressure generating unit.
In this variant of the invention, the partitions are replaced with gas or liquid volumes. These gases or liquids are inert and substantially not miscible with the reagents. The liquids are hydrophobic. In the outlet opening, there is a hydrophilic membrane allowing only the reagents to pass but not the hydrphobic separating liquids or the gaseous separating volumes. In the initial state of the device according to this variant, a closure is arranged in the region of the outlet device dosing the same from inside. The use of liquid or gas volumes for separation requires the receptacle to be configured as a capillary. This capillary is open at its two opposite ends and has a branch adjoining the outlet opening.
Below the outlet opening, between the same and the lower first end of the capillary, the holding force generating device, already mentioned in connection with the partition elements of the first variant of the invention, is provided, now cooperating with the closure. Therefore, all above explanations regarding the holding force generating device apply analogously to the second variant of the invention.
The following is a detailed discussion of embodiments of the invention with reference to the drawings.